In my current game we have a warforged artificer. He is definitely a Leader and Arcane.
Here is my little rant on this: He deals with magic items crafting, repairing and figuring out magic items. Without having played with one before I thought they were sort of a "tech" like class but they are alas not, much to my chagrin. They are simply magic item guys that can deal with traps. This is an integral part of the Eberron shtick, they are why their are so many magic items in Eberron. If they wind up being anything else than an Arcane Leader, they will be short changing the legacy of Eberron. Their "spells" called "infusions" just boost, enhance and repair magical objects/items/things.
Now for my rant on Warforged <please skip now> (I needed an outlet...) Warforged are ridiculously powered. They are immune to everything. And have nearly no draw backs. They can still be healed at half rate with cures and are immune to almost every condition thrown at us. From the top of my head: fatigue, exhaustion, level drain, paralysis, poison, sleep, nausea, disease, sickened, with no need to sleep, breathe, or eat, and has +2 natural armor, light fortification magic item ability a slam attack and at the cost of a mere feat they get adamantine full plate with DR 3/-. With very little drawback, they easily upstage other races. Things that we thought would be cool to limit them is that they are loud, sort of like a steam engine, have a smoke stack, need to power themselves with something some special material like coal or steam or something and could even be magic "batteries"- this would be their "food" you know the stuff regular adventurers have to carry around. Also, a shutoff switch or "sleep" mode, so that they don't expend their "food". The Tin-Man didn't like water and the Warforged shouldn't either, they should have to dry themselves and try not to submerge themselves so that they don't get rusty or "corroded", of which corroded should be a "condition" that only they can get, in fact they should have several conditions that only they can get- so that all those immunities are fine but they have their own list.